Insertion tool

ABSTRACT

A tool for inserting into a cavity is provided. The tool includes a plurality of segments moveably coupled to one another, each segment moveable relative to an adjacent segment between a bent position and a coupled position, the plurality of segments including a first segment, the first segment including: a core formed of a first material; and a shell formed of a second material and comprising or defining a guide feature, a drive feature, a line guide, or a combination thereof; wherein the first material defines a greater stiffness than the second material.

FIELD

The present subject matter relates generally to a tool for inspecting anenvironment and/or performing maintenance operations on a componentwithin the environment, such as within an annular space in a turbineengine.

BACKGROUND

At least certain gas turbine engines include, in serial flowarrangement, a compressor section including a low pressure compressorand a high-pressure compressor for compressing air flowing through theengine, a combustor for mixing fuel with the compressed air such thatthe mixture may be ignited, and a turbine section including a highpressure turbine and a low pressure turbine for providing power to thecompressor section.

Within one or more of the sections, at least certain gas turbine enginesdefine an annular opening. Certain of these annular openings may vary insize, such that a dedicated, specialized insertion tool must be utilizedwith each annular opening to extend around and through such annularopening.

The inventors of the present disclosure have come up with an insertiontool that may be inserted into an annular opening. The insertion toolthat the inventors have come up with may benefit from the inclusion ofrelatively complex geometries and features. Accordingly, an insertiontool formed in a manner that meets these needs would be useful.

BRIEF DESCRIPTION

Aspects and advantages of the invention will be set forth in part in thefollowing description, or may be obvious from the description, or may belearned through practice of the invention.

In one embodiment of the present disclosure, a tool for inserting into acavity is provided. The tool includes a plurality of segments moveablycoupled to one another, each segment moveable relative to an adjacentsegment between a bent position and a coupled position, the plurality ofsegments including a first segment, the first segment including: a coreformed of a first material; and a shell formed of a second material andcomprising or defining a guide feature, a drive feature, a line guide,or a combination thereof; wherein the first material defines a greaterstiffness than the second material.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdescription and appended claims. The accompanying drawings, which areincorporated in and constitute a part of this specification, illustrateembodiments of the invention and, together with the description, serveto explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including thebest mode thereof, directed to one of ordinary skill in the art, is setforth in the specification, which makes reference to the appendedfigures, in which:

FIG. 1 is a schematic, cross-sectional view of a gas turbine engine inaccordance with an exemplary aspect of the present disclosure.

FIG. 2 is a close-up, cross-sectional view of a combustion section ofthe exemplary gas turbine engine of FIG. 1 including an insertion toolin accordance with an exemplary embodiment of the present disclosure,along an axial direction and a radial direction.

FIG. 3 is another close-up, cross-sectional view of the combustionsection of the exemplary gas turbine engine of FIG. 1 including theexemplary insertion tool, along the radial direction and acircumferential direction.

FIG. 4 is a close-up view of a drive portion of the exemplary insertiontool of FIG. 3.

FIG. 5 is a close-up view of an insertion portion of the exemplaryinsertion tool of FIG. 4.

FIG. 6 is a close-up view of a portion of the exemplary insertion toolof FIG. 4 in a coupled position.

FIG. 7 is a perspective view of a segment of an insertion tool inaccordance with an exemplary embodiment of the present disclosure.

FIG. 8 is close-up view of a portion of the exemplary insertion tool ofFIG. 7 in a coupled position.

FIG. 9 is an end view of the exemplary segment of FIG. 7.

DETAILED DESCRIPTION

Reference will now be made in detail to present embodiments of theinvention, one or more examples of which are illustrated in theaccompanying drawings. The detailed description uses numerical andletter designations to refer to features in the drawings. Like orsimilar designations in the drawings and description have been used torefer to like or similar parts of the invention.

As used herein, the terms “first”, “second”, and “third” may be usedinterchangeably to distinguish one component from another and are notintended to signify location or importance of the individual components.

The terms “forward” and “aft” refer to relative positions of a componentor system. For example, with respect to a gas turbine engine, theseterms refer to the normal operational attitude of the gas turbine engineor vehicle (e.g., with forward referring to a position closer to anengine inlet and aft referring to a position closer to an engine nozzleor exhaust). Similarly, with other components, these terms refer to anormal operational attitude of the component, such that forward refersto a position closer to a leading end and aft refers to a positioncloser to a trailing end.

The terms “upstream” and “downstream” refer to the relative directionwith respect to fluid flow in a fluid pathway. For example, “upstream”refers to the direction from which the fluid flows, and “downstream”refers to the direction to which the fluid flows.

The terms “coupled,” “fixed,” “attached to,” and the like refer to bothdirect coupling, fixing, or attaching, as well as indirect coupling,fixing, or attaching through one or more intermediate components orfeatures, unless otherwise specified herein.

The singular forms “a”, “an”, and “the” include plural references unlessthe context clearly dictates otherwise.

Approximating language, as used herein throughout the specification andclaims, is applied to modify any quantitative representation that couldpermissibly vary without resulting in a change in the basic function towhich it is related. Accordingly, a value modified by a term or terms,such as “about”, “approximately”, and “substantially”, are not to belimited to the precise value specified. In at least some instances, theapproximating language may correspond to the precision of an instrumentfor measuring the value, or the precision of the methods or machines forconstructing or manufacturing the components and/or systems. Forexample, the approximating language may refer to being within a 10percent margin.

Here and throughout the specification and claims, range limitations arecombined and interchanged, such ranges are identified and include allthe sub-ranges contained therein unless context or language indicatesotherwise. For example, all ranges disclosed herein are inclusive of theendpoints, and the endpoints are independently combinable with eachother.

Referring now to the drawings, wherein identical numerals indicate thesame elements throughout the figures, FIG. 1 is a schematiccross-sectional view of a gas turbine engine in accordance with anexemplary embodiment of the present disclosure. More particularly, forthe embodiment of FIG. 1, the gas turbine engine is a high-bypassturbofan jet engine 10, referred to herein as “turbofan engine 10.” Asshown in FIG. 1, the turbofan engine 10 defines an axial direction A(extending parallel to a longitudinal centerline 12 provided forreference) and a radial direction R. The turbofan engine 10 also definesa circumferential direction C (see FIG. 3) extending circumferentiallyabout the axial direction A. In general, the turbofan 10 includes a fansection 14 and a turbomachine 16 disposed downstream from the fansection 14.

The exemplary turbomachine 16 depicted is generally enclosed within asubstantially tubular outer casing 18 that defines an annular inlet 20and an annular exhaust 21. The outer casing 18 encases, in serial flowrelationship, a compressor section including a booster or low pressure(LP) compressor 22 and a high pressure (HP) compressor 24; a combustionsection 26; a turbine section including a high pressure (HP) turbine 28and a low pressure (LP) turbine 30; and a jet exhaust nozzle section 32.A high pressure (HP) shaft or spool 34 drivingly connects the HP turbine28 to the HP compressor 24. A low pressure (LP) shaft or spool 36drivingly connects the LP turbine 30 to the LP compressor 22. Thecompressor section, combustion section 26, turbine section, and nozzlesection 32 together define a core air flowpath 37 therethrough.

For the embodiment depicted, the fan section 14 includes a fixed pitchfan 38 having a plurality of fan blades 40. The fan blades 40 are eachattached to a disk 42, with the fan blades 40 and disk 42 togetherrotatable about the longitudinal axis 12 by the LP shaft 36. For theembodiment depicted, the turbofan engine 10 is a direct drive turbofanengine, such that the LP shaft 36 drives the fan 38 of the fan section14 directly, without use of a reduction gearbox. However, in otherexemplary embodiments of the present disclosure, the fan 38 may insteadbe a variable pitch fan, and the turbofan engine 10 may include areduction gearbox, in which case the LP shaft 36 may drive the fan 38 ofthe fan section 14 across the gearbox.

Referring still to the exemplary embodiment of FIG. 1, the disk 42 iscovered by rotatable front hub 48 aerodynamically contoured to promotean airflow through the plurality of fan blades 40. Additionally, theexemplary turbofan engine 10 includes an annular nacelle assembly 50that circumferentially surrounds the fan 38 and/or at least a portion ofthe turbomachine 16. For the embodiment depicted, the nacelle assembly50 is supported relative to the turbomachine 16 by a plurality ofcircumferentially-spaced outlet guide vanes 52. Moreover, a downstreamsection 54 of the nacelle assembly 50 extends over an outer portion ofthe casing 18 so as to define a bypass airflow passage 56 therebetween.The ratio between a first portion of air through the bypass airflowpassage 56 and a second portion of air through the inlet 20 of theturbomachine 16, and through the core air flowpath 37, is commonly knownas a bypass ratio.

It will be appreciated that although not depicted in FIG. 1, theturbofan engine 10 may further define a plurality of openings allowingfor inspection of various components within the turbomachine 16. Forexample, the turbofan engine 10 may define a plurality of borescopeopenings at various axial positions within the compressor section,combustion section 26, and turbine section. Additionally, as will bediscussed below, the turbofan engine 10 may include one or more igniterports within, e.g., the combustion section 26 of the turbomachine 16,that may allow for inspection of the combustion section 26.

It should further be appreciated that the exemplary turbofan engine 10depicted in FIG. 1 is by way of example only, and that in otherexemplary embodiments, the turbofan engine 10 may have any othersuitable configuration, including, for example, any other suitablenumber of shafts or spools, turbines, compressors, etc. Additionally, oralternatively, in other exemplary embodiments, any other suitableturbine engine may be provided. For example, in other exemplaryembodiments, the turbine engine may not be a turbofan engine, andinstead may be configured as a turboshaft engine, a turboprop engine,turbojet engine, etc.

Referring now to FIG. 2, a close-up, schematic view of the combustionsection 26 of the turbomachine 16 of the exemplary gas turbine engine 10of FIG. 1 is provided along with a tool 100 for insertion into anannular section of the engine 10. It will be appreciated that althoughthe tool 100 is depicted in FIG. 2, and described below, as beinginserted into a combustion section 26, in other exemplary embodiments,the tool 100 may additionally, or alternatively, be inserted into otherareas of the turbofan engine 10 having an annular shape or other shape.For example, the tool 100 may be inserted into annular sections of thecompressor section or the turbine section, or alternatively still, otherengines or systems altogether. Additionally or alternatively, still, thetool 100 may be inserted into a non-annular section.

As is depicted, the combustion section 26 generally includes a combustor60 positioned within a combustor casing 62. Additionally, the combustor60 includes an inner liner 64, an outer liner 66, and a dome 68 togetherdefining at least in part a combustion chamber 70. It will beappreciated that the dome 68, for the embodiment depicted, is an annulardome and the combustor 60 is configured as an annular combustor. In sucha manner, the combustion chamber 70 generally defines an annular shape.At a forward end 61, the combustor 60 defines, or rather, the dome 68defines, a nozzle opening 72, and the combustion section 26 furtherincludes a fuel-air mixer 74, or nozzle, positioned within the nozzleopening 72. The fuel-air mixer 74 is configured to provide a mixture offuel and compressed air to the combustion chamber 70 during operation ofthe turbofan engine 10 to generate combustion gases. The combustiongases flow from the combustion chamber 70 to the HP turbine 28, and morespecifically, through a plurality of inlet guide vanes 76 of the HPturbine 28.

Notably, although a single nozzle opening 72 and fuel-air mixer 74 isdepicted in FIG. 2, the combustor 60 may further include a plurality ofcircumferentially spaced nozzle openings 72 and a respective pluralityof fuel-air mixers 74 positioned within the nozzle openings 72.

In order to initiate a combustion of the fuel and compressed airprovided to the combustion chamber 70 by the fuel-air mixer 74, thecombustion section 26 typically includes one or more igniters (notinstalled or depicted) extending through respective igniter openings 78defined in the combustor casing 62 and the outer liner 66 of thecombustor 60. However, when the turbofan engine 10 is not operating, theigniter(s) may be removed and the igniter opening(s) 78 may be utilizedfor inspecting, e.g., the combustion chamber 70, inlet guide vanes 76 ofthe HP turbine 28, and/or other components.

More specifically, for the embodiment of FIG. 2, the tool 100 capable ofinsertion into an annular section of an engine is depicted extendingthrough the pair of igniter openings 78 defined in the combustor casing62 and the outer liner 66 of the combustor 60.

Referring now also to FIG. 3, providing a partial, axial cross-sectionalview of the combustion section 26 of FIG. 2, it will be appreciated thatthe tool 100 generally includes a plurality of segments 102 and aninsertion tube 104, with the plurality of segments 102 movable throughthe insertion tube 104 into the combustion chamber 70.

Additionally, for the exemplary embodiment depicted, the insertion tube104 includes a bend 106. For the embodiment shown, the bend 106 is asubstantially 90 degree bend. For example, the insertion tube 104includes a radial portion 108 extending substantially along the radialdirection R and a circumferential portion 110 extending substantiallyalong the circumferential direction C. The radial portion 108 andcircumferential portion 110 are joined at the bend 106. The plurality ofsegments 102 are fed through the radial portion 108, pivot in a firstangular direction relative to one another to go through the bend 106,and then pivot in a second, opposite angular direction relative to oneanother and couple to one another such that they are in a fixed positionrelative to one another as they move through to the circumferentialportion 110. From the circumferential portion 110, the segments 102extend through the annular combustion chamber 70.

Further, a forward-most segment 102′ includes an implement, which forthe embodiment depicted is a camera 111, to allow the user to inspectvarious components of the combustor 60 and/or high pressure turbine 28.It will be appreciated, however, that the insertion tool 100 may includeany other suitable implement, such that the insertion tool 100 may beutilized for any suitable purpose. For example, the insertion tool 100may be utilized to inspect the interior of the engine using, e.g., thecamera 111. Additionally, or alternatively, the insertion tool 100 mayinclude various other tool implements to perform one or more maintenanceoperations within the interior of the engine (e.g., drilling, welding,heating, cooling, cleaning, spraying, etc.).

Further, the exemplary insertion tool 100 includes a drive assembly 112for driving the plurality of segments 102 of the insertion tool 100into, or out of, the interior of the engine, and more specifically forthe embodiment shown, into or out of the combustion chamber 70, throughthe insertion tube 104. Referring now briefly to FIG. 4, providing aclose-up, schematic view of the drive assembly 112 and a single segment102 of the plurality of segments 102, it will be appreciated that theexemplary drive assembly 112 generally includes a drive wheel 114 and adrive motor 116. The drive wheel 114 includes a plurality of drive gearteeth 118 spaced along a circumference thereof, and the drive motor 116is configured to rotate the drive wheel 114. For the embodiment shown,and as will be described in more detail below, each segment 102 of theplurality of segments 102 includes a drive feature, which for theembodiment shown, is a plurality of segment gear teeth 120. Theplurality of segment gear teeth 120 of the segment 102 are eachconfigured to mesh with the plurality of drive gear teeth 118 of thedrive wheel 114, such that rotation of the drive wheel 114 by the drivemotor 116 moves the segment 102 along a longitudinal direction 122 ofthe segment 102.

Although not depicted, it will be appreciated that the drive motor 116may be operably coupled to a controller or other control device, suchthat a length of the insertion tool 100 within the interior of theengine may be controlled with relative precision by the drive assembly112.

Referring now to FIG. 5, a close-up view of a portion of the tool 100 ofFIGS. 2 and 3 is provided. Specifically, FIG. 5 provides a close-up viewof four segments 102 of the plurality of segments 102 of the tool 100extending through the bend 106 of the insertion tube 104. The segments102 generally include a first segment 102A, a second segment 102B, athird segment 102C, and a fourth segment 102D.

Each of the segments 102 extend generally along a respectivelongitudinal direction 122 between a forward end 124 and an aft end 126,with the aft end 126 of one segment 102 being pivotably coupled to theforward end 124 of an aft-adjacent segment 102, and the forward end 124of the segment 102 being pivotably coupled to the aft end 126 of aforward-adjacent segment 102. It will be appreciated, that as usedherein, the term “longitudinal direction” with respect to a particularsegment 102 refers to a direction extending between pivot axes 128 atthe forward end 124 and aft end 126 of the segment 102 where the segment102 is coupled to the adjacent segments 102, in a plane perpendicular tothese pivot axes 128.

For example, the forward end 124 of the first segment 102A is pivotablycoupled to the aft end 126 of the second segment 102B, the forward end124 of the second segment 102B is pivotably coupled to the aft end 126of the third segment 102C, and the forward end 124 of the third segment102C is pivotably coupled to the aft end 126 of the fourth segment 102D.

Notably, each of the first segment 102A, second segment 102B, thirdsegment 102C, and fourth segment 102D defines a respective outer side132 and a respective inner side 130. The forward end 124 of the firstsegment 102A and the aft end 126 of the second segment 102B arepivotably coupled at their respective outer sides 132. Similarly, theforward end 124 of the second segment 102B and the aft end 126 of thethird segment 102C are pivotably coupled at their respective outer sides132, and the forward end 124 of the third segment 102C and the aft end126 of the fourth segment 102D are pivotably coupled at their respectiveouter sides 132. It will be appreciated, however, that in otherexemplary embodiments, the segments 102 may instead be pivotably coupledto one another at their respective inner sides 130, or a locationbetween their respective outer and inner sides 132, 130.

Referring now also to FIG. 6, a close-up view of the plurality ofsegments 102 of FIG. 5 are depicted extending through the combustionchamber 70 (not labeled; see FIGS. 2 and 3). As is depicted in FIGS. 5and 6, the tool 100 additionally includes a biasing member, and morespecifically a line assembly having one or more lines 134 configured tobias the segments 102 towards their respective coupled positions(discussed below).

For the embodiment shown, and as will be explained in more detail below,the line 134 extends through the plurality of segments 102, andspecifically, for the embodiment shown, through at least the firstsegment 102A, the second segment 102B, the third segment 102C, and thefourth segment 102D. As stated, the line 134 is configured to bias thesegments 102 towards their respective coupled positions (discussedbelow), for example, to bias the first segment 102A towards the coupledposition relative to the second segment 102B. For the embodiment shown,the line 134 is configured to extend through line guides 136 (see FIG.7, discussed below) within each of the segments 102 for providing abiasing force to press the segments 102 together.

In certain exemplary embodiments, the line 134 may be configured as ametal line, or any other suitable material or line. However, in stillother embodiments, any other suitable biasing member may be provided.For example, in other embodiments, the line 134 may be a plurality oflines, with each line 134 extending between a pair of adjacent segments102 of the tool 100, or alternatively, with each line 134 extending froma base of the tool 100 to an individual segment 102 to provide thebiasing of the individual segment 102 towards a coupled positionrelative to an aft-adjacent segment 102. Additionally, or alternatively,the biasing member may be a plurality of springs extending betweenadjacent segments 102, with each spring oriented axially to pull thesegments 102 together, or torsionally to bendably bias the segments 102towards each other by rotation about their respective axis 128. Further,in still other exemplary embodiments, the biasing member may not be atension member, and instead may be any other suitable biasing member,such as one or more magnets and/or ferromagnetic materials.

Referring now to FIGS. 7 and 8, views of a tool 100 in accordance withan embodiment of the present disclosure are provided. In particular,FIG. 7 provides a perspective view of an individual segment 102 of aplurality of segments 102 of the exemplary tool 100, and FIG. 8 providesa side view of two segments 102 of the plurality of segments 102 of theexemplary tool. The exemplary tool 100 of FIGS. 7 and 8 may beconfigured in a similar manner to the tool 100 described above withrespect to FIGS. 5 and 6. As will be appreciated from the views of thesegments 102 depicted in FIGS. 7 and 8, each segment 102 of theplurality of segments 102 is formed of at least two different materialsspecifically designed to impart particular mechanical properties to eachsegment 102 of the plurality of segments 102.

Specifically, for the embodiment affected, the segment 102 includes acore 140 formed of a first material and a shell 142 formed of a secondmaterial. The first material defines a first material stiffness, and thesecond material defines a second material stiffness. The stiffness ofthe first material is greater than the stiffness of the second material.Specifically, in at least certain exemplary embodiments, the firstmaterial stiffness is at least about five (5) times greater than thesecond material stiffness as measured in a suitable engineering unit forstiffness, such as gigapascals (GPa). For example, in at least certainexemplary embodiments, the first material stiffness may be at leastabout 20 times greater than the second material stiffness, such as atleast about 50 times greater than the second material stiffness (seealso discussion below).

Referring particularly to FIG. 8, it will be appreciated that the core140 of the segment 102 depicted in FIG. 7 is configured to abut a core140 of a forward-adjacent segment 102, as well as a core 140 of anaft-adjacent segment 102 (see also, e.g., FIG. 6). For example, in theembodiment of FIG. 8, it will be appreciated that the core 140 of thesecond segment 102B is configured to abut core 140 of the first segment102A, and is further configured to abut the core 140 of a third segment(not shown, see segment 102C of FIG. 6).

In such a manner, it will be appreciated that the plurality of segments102, when in the coupled position, may define a desired overallstiffness for the tool 100. More specifically, by having the core 140 ofeach segment 102 abut the cores 140 of the adjacent segments 102, theplurality of segments 102 when in the coupled position may togetherdefine the desired overall stiffness for the tool 100, allowing the tool100 to extend a desired length within the environment, while still beingcapable of moving with a desired precision and/or carry a desired load.

For example, in certain exemplary embodiments, the first material,forming the core 140 of the segment 102, may be a relatively stiffmaterial defining a stiffness greater than about 100 GPa, such asgreater than about 125 GPa, such as greater than about 175 GPa, such asup to about 12,000 GPa. By contrast, the second material, forming theshell 142 of the segment 102, maybe a relatively low stiffness materialdefining a stiffness less than about 100 GPa, such as less than about 75GPa, such as less than about 50 GPa, such as less than about 25 GPa,such as at least about 0.01 GPa. By way of example, the first materialmay be one or more of a metal material (such as a titanium or titaniumalloy, copper, steel, or stainless steel), may be a ceramic material(such as a reinforced ceramic, such as a whisker reinforced ceramic orother fiber reinforced ceramic), may be a carbon fiber reinforcedplastic, etc. Also by way of example, the second material may be one ormore of a polymer, a plastic polymer (such as an acetal polymer,acrylonitrile butadiene styrene (ABS), polycarbonate (PC), polycarbonate(PC), polystyrene, or polyvinyl chloride (PVC)), may be a rubbermaterial, etc.

In such a manner, it will be appreciated that the core 140 may be formedthrough one or more traditional manufacturing methods, such as bycasting, extruding, 3D printing/additive manufacturing, etc. Given therelative simplicity of the geometry of the core 140, it may berelatively easy to form the core 140 with a relatively hard and stiffmaterial through a variety of manufacturing methods.

By contrast, the shell 142 of the segment 102 may be overmolded onto thecore 140 subsequent to the formation of the core 140. For the embodimentshown, the shell 142 substantially completely covers an entirety of anexterior of the core 140. For example, in only certain exemplaryembodiments, the shell 142 may cover at least about 75% of the exteriorof the core 140, such as at least about 90% of the exterior of the core140 (with the “exterior” of the core 140 being the portion of the core140 that would otherwise be viewable when the plurality of segments 102are in the coupled position). In such a manner, it will be appreciatedthat the shell 142 of the segment 102 may be formed through a thermalmelt-based molding process. However, in other embodiments, the shell 142of the segment 102 may be formed through any other suitable process,such as through a reaction injection molding process, which may moreeasily allow for molding of materials which are not plastics.

As will be explained in more detail below, the shell 142 may includemore complex geometries than the core 140, such that it may berelatively easy to form the shell 142 with a more moldable material,such as one or more of the materials listed above as exemplary secondmaterials. Further, forming the segment 102 in such a manner may allowfor features included with or defined by the shell 142 of the segment102 to have different mechanical properties than the core 140.

As noted above, the shell 142 of the core 140 may include or define morecomplex geometries than the core 140. Specifically, in the embodimentshown, the shell 142 includes or defines a guide feature, a drivefeature, a line guide 136, or a combination thereof. More specifically,for the embodiment shown, the shell 142 includes or defines each of theguide feature, the drive feature, and the line guide 136.

For example, the drive feature of the shell 142 includes the pluralityof segment gear teeth 120, which are configured to mesh with theplurality of drive gear teeth 118 of the drive assembly 112 describedabove with reference to FIG. 4. In such a manner, the plurality ofsegment gear teeth 120 to be configured to move the segment 102 forwardor back during operation. It will be appreciated, however, that in otherembodiments, the drive feature of the shell 142 may be configured in anyother suitable manner. For example, in other embodiments, the drivefeature may be one or more differently configured drive gear teeth 118,or alternatively may be any other suitable geometry for providingfriction for a drive assembly 112, such as the exemplary drive wheel114, to grip the segment 102 and move segment 102 forward or back. Forexample, the drive feature may be a plurality of ridges, or otherstructure.

Also as noted above, utilizing a different second material for the shell142 and the first material for the core 140 may allow for the shell 142to have different mechanical properties than the core 140. For example,as discussed above, it may be important for the core 140 to have arelatively high stiffness, such that the tool 100 defines a relativelyhigh overall stiffness during operation. However, such may not necessarybe a mechanical property that is important or desirable for shell 142.In particular, for the embodiment discussed herein with respect to FIGS.7 and 8, it may be desirable for the drive feature of the shell 142 tobe configured to wear more quickly than, e.g., the drive gear teeth 118of the drive wheel 114. For example, it will be appreciated that thesecond material defines a second material hardness and the drive gearteeth 118 of the drive wheel 114 may be formed of a material defining amaterial hardness greater than the second material hardness. In suchmanner, the drive feature of the shell 142 may be configured to weardown more quickly than the drive gear teeth 118 of the drive wheel 114,which may be desirable given that each drive gear tooth 118 is likely toengage with segment gear teeth 120 many more times than each segmentgear tooth 120 is likely to engage with drive gear teeth 118.

In addition, the shell 142, formed of the second material, includes theguide feature. For the embodiment shown, the guide feature is a segmentsliding plain bearing feature 144. The segment sliding plain bearingfeature 144 may be configured to guide the segment 102 through theinsertion tube 104, while also ensuring the segment 102 maintains adesired orientation within the insertion tube 104. Specifically,referring now also to FIG. 9, providing an end view of one of thesegments 102 in FIG. 8, positioned within an insertion tube 104, it willbe appreciated that the insertion tube 104 similarly includes a tubesliding plain bearing feature 146. The tube sliding plain bearingfeature 146 is configured to interact with the segment sliding plainbearing feature 144. In particular, it will be appreciated that for theembodiment shown, the tube sliding plain bearing feature 146 isconfigured as a channel or other indentation in a wall of the insertiontube 104, and the segment sliding plain bearing feature 144 isconfigured as a linear protrusion extending outward from the core 140(and proud of the surrounding portions of the shell 142) and along thelongitudinal direction 122 of the segment 102. In such a manner, thesegment sliding plain bearing feature 144 may be positioned at leastpartially within the tube sliding plain bearing feature 146 to preventthe segment 102 from becoming misaligned or twisted out of orientationwhen being inserted through the insertion tube 104.

Notably, by forming the shell 142 of the second material, separate fromthe first material of the core 140, the shell 142 may be formed ofmaterial to facilitate the segment sliding plain bearing feature 144operating as desired with, e.g., the tube sliding plain bearing feature146. For example, it will be appreciated that in only certain exemplaryembodiments, such as exemplary embodiment depicted, the first materialmay define a first coefficient of friction and the second material maydefine a second coefficient of friction. The first coefficient offriction is at least about fifteen percent greater than the secondcoefficient of friction (i.e., μ(first material)=μ(secondmaterial)×1.15). Specifically, in at least some embodiments, the firstcoefficient of friction may be at least about thirty percent greaterthan the second coefficient of friction, such as at least about fiftypercent greater than the second session of friction, such as up to about1,000% greater than the second coefficient of friction. Such aconfiguration may enable the segment 102 to relatively easily slidealong within the insertion tube 104, without necessitating, e.g.,lubricated bearings or other more complex mechanical structures,lubrications, etc.

Further, as with the drive feature, it may be beneficial for the segmentsliding plain bearing feature 144 to wear more quickly than the tubesliding plain bearing feature 146 of the insertion tube 104. As such, itwill be appreciated that in at least certain exemplary embodiments, amaterial hardness of the material forming or defining the tube slidingplain bearing feature 144 may be greater than the second materialhardness of the second material forming the shell 142 and the segmentsliding plain bearing feature 144.

It will be appreciated, however, that although the exemplary tool 100depicted includes sliding plain bearing features 144, 146, in otherexemplary embodiments, other guide features may be provided. Forexample, in other embodiments, the shell 142 of the segments 102 mayincorporate a roller bearing design, or the tube sliding plain bearingfeature 146 may additionally or alternatively utilize a roller bearingdesign. Additionally, or alternatively, still, one or both of thesliding plain bearing features 144, 146 may be replaced with orsupplemented with, e.g., air bearing features, lubrication bearingfeatures, etc.

Moreover, as noted above, the shell 142 includes the line guide 136. Forthe embodiment shown, the line guide 136 extends substantially from theforward end 124 of the segment 102 to the aft end 126 of the segment 102along the longitudinal direction 122 the segment 102. As discussedabove, the second material may define a relatively low coefficient offriction. Such may assist with threading the line 134 through the lineguides 136 of the various segments 102. As also discussed above, thesecond material may define a relatively low material hardness. Incertain exemplary embodiments, the line 134 may be formed of a linematerial defining a line material hardness greater than the secondmaterial hardness. Such may ensure that operation of the tool 100 doesnot appreciably wear down the line 134, such wear potentially resultingin a failure of the tool 100 within an environment.

Referring to FIGS. 7 and 8, it will be appreciated that adjacentsegments 102 are pivotably contacting one another at a joint 152, whichfor the embodiment shown is positioned generally at the outer side 132.The joint 152 is formed, for the embodiment shown, of a pair of roundedprotrusions 154 on a first segment 102A and a corresponding pair ofindention members 156 on a second segment 102B (see FIG. 8). The roundedprotrusions 154 and indention members 156 have corresponding geometries,and each of the pair of rounded protrusions 154 and indention members156 are spaced from one another in a cross-wise direction along thepivot axis 128. The rounded protrusions 154 and indention members 156are, for the embodiment shown, formed as part of the core 140. However,the segments 102 shown further include an alignment feature 158positioned between one of the pair of rounded protrusions 154 or pair ofindention members 156 for extending into an opening between the other ofthe pair of rounded protrusions 154 or indention members 156.Particularly for the embodiment shown the alignment feature 158 ispositioned between the pair of rounded protrusions 154 and extendsbetween the pair of indention members 156 to assist with aligning theadjacent segments 102. For the embodiment shown, the alignment feature158 is formed as part of the shell 142.

Briefly, referring still to FIG. 8, it will be appreciated that thesegments 102 may define an interior opening 148 allowing for supportingstructure for the various tool implements described above. Inparticular, for the embodiment shown, the tool 100 includes a variety ofstructures 150 extending along a length of the plurality of structuresencasing, e.g., fluid flow paths, electrical lines, etc. In such amanner, the opening through the plurality of segments 102 may enableoperation of a wide variety of tool implements at, e.g., a distal end ofthe plurality of segments 102, such as at the forward-most segment 102′.

In view of the above description, it will be appreciated that formingthe shell 142 of the second material may allow for a segment 102 thatmaintains a desired stiffness and strength, while also having a varietyof relatively complex geometry features, with these relatively complexgeometry features defining material properties having specific benefitsthat would otherwise be difficult to obtain. Moreover, forming the shell142 of the second material may reduce the weight of the segment 102, andtherefore, a weight of the tool 100.

Further aspects of the invention are provided by the subject matter ofthe following clauses:

A tool for inserting into a cavity, the tool comprising a plurality ofsegments moveably coupled to one another, each segment moveable relativeto an adjacent segment between a bent position and a coupled position,the plurality of segments comprising a first segment, the first segmentcomprising: a core formed of a first material; and a shell formed of asecond material and comprising or defining a guide feature, a drivefeature, a line guide, or a combination thereof; wherein the firstmaterial defines a greater stiffness than the second material.

The tool of any of the preceding clauses, wherein the core of the firstsegment is configured to abut a core of a forward adjacent segment and acore of an aft-adjacent segment.

The tool of any of the preceding clauses, wherein the shell comprisesthe drive feature, wherein the drive feature is a plurality of gearteeth.

The tool of any of the preceding clauses, wherein the shell comprisesthe guide feature, and wherein the guide feature is a segment bearingfeature.

The tool of any of the preceding clauses, wherein the first materialdefines a first coefficient of friction, wherein the second materialdefines a second coefficient of friction, and wherein the firstcoefficient of friction is at least about fifteen percent greater thanthe second coefficient of friction.

The tool of any of the preceding clauses, wherein the segment bearingfeature is a segment sliding bearing feature, and wherein the toolfurther comprises: an insertion tube comprising a tube sliding plainbearing feature configured to interact with the segment sliding plainbearing feature, wherein the tube sliding plain bearing feature isformed of a third material defining a third material hardness greaterthan a second material hardness of the second material.

The tool of any of the preceding clauses, wherein the shell comprisesthe line guide.

The tool of any of the preceding clauses, wherein the first segmentdefines a local longitudinal direction, a first end, and a second end,and wherein the line guide extends substantially from the first end tothe second end along the local longitudinal direction.

The tool of any of the preceding clauses, further comprising: a tensionline configured to hold the segments in the coupled position, whereinthe tension line is formed of a line material defining a line materialhardness greater than a second material hardness of the second material.

The tool of any of the preceding clauses, wherein the first material isa metal material, a ceramic material, or a combination thereof, andwherein the second material is a polymer material.

The tool of any of the preceding clauses, wherein the first materialdefines a first material stiffness, wherein the second material definesa second material stiffness, and wherein the first material stiffness isat least five times greater than the second material stiffness.

The tool of any of the preceding clauses, wherein the tool is configuredas an insertion tool, and wherein the cavity is an annular cavity of agas turbine engine.

The tool of any of the preceding clauses, wherein the shell of the firstsegment is overmolded onto the core, and wherein the shell substantiallycovers an entirety of an exterior of the core.

A gas turbine engine assembly comprising: a component defining anopening to a cavity within the gas turbine engine; and an insertion toolextending through the opening defined by the component into the cavity,the insertion tool comprising a plurality of segments moveably coupledto one another, each segment moveable relative to an adjacent segmentbetween a bent position and a coupled position, the plurality ofsegments comprising a first segment, the first segment comprising a coreformed of a first material, and a shell formed of a second material andcomprising or defining a guide feature, a drive feature, a line guide,or a combination thereof, wherein the first material defines a greaterstiffness than the second material.

The gas turbine engine of any of the preceding clauses, wherein thecavity is an annular cavity of the gas turbine engine.

The gas turbine engine of any of the preceding clauses, wherein the coreof the first segment is configured to abut a core of a forward adjacentsegment and a core of an aft-adjacent segment.

The gas turbine engine of any of the preceding clauses, wherein theshell comprises the drive feature, wherein the drive feature is aplurality of gear teeth.

The gas turbine engine of any of the preceding clauses, wherein theshell comprises the guide feature, and wherein the guide feature is asegment sliding plain bearing feature.

The gas turbine engine of any of the preceding clauses, wherein thefirst material defines a first coefficient of friction, wherein thesecond material defines a second coefficient of friction, and whereinthe first coefficient of friction is at least about fifteen percentgreater than the second coefficient of friction.

The gas turbine engine of any of the preceding clauses, wherein theshell comprises the line guide.

This written description uses examples to disclose the invention,including the best mode, and also to enable any person skilled in theart to practice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they include structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A tool for inserting into a cavity, the toolcomprising: a plurality of segments moveably coupled to one another,each segment moveable relative to an adjacent segment between a bentposition and a coupled position, the plurality of segments comprising afirst segment, the first segment comprising: a core formed of a firstmaterial; a shell formed of a second material and comprising a guidefeature, a drive feature, a line guide, or a combination thereof;wherein the first material defines a greater stiffness than the secondmaterial; wherein the guide feature includes a dedicated bearing surfaceon the shell; wherein the drive feature includes a repeating surfaceprofile on the shell; and wherein a tension line extends through theline guide to continuously bias the first segment toward the coupledposition with an adjacent segment of the plurality of segments.
 2. Thetool of claim 1, wherein the core of the first segment is configured toabut a core of a forward adjacent segment and a core of an aft-adjacentsegment.
 3. The tool of claim 1, wherein the repeating surface profileis a plurality of gear teeth.
 4. The tool of claim 1, wherein the firstsegment defines a local longitudinal direction, a first end, and asecond end, and wherein the line guide extends substantially from thefirst end to the second end along the local longitudinal direction. 5.The tool of claim 1, wherein the tension line is configured to hold theplurality of segments in the coupled position, and wherein the tensionline is formed of a line material defining a line material hardnessgreater than a second material hardness of the second material.
 6. Thetool of claim 1, wherein the first material is a metal material, aceramic material, or a combination thereof, and wherein the secondmaterial is a polymer material.
 7. The tool of claim 1, wherein thefirst material defines a first material stiffness, wherein the secondmaterial defines a second material stiffness, and wherein the firstmaterial stiffness is at least five times greater than the secondmaterial stiffness.
 8. The tool of claim 1, wherein the tool isconfigured as an insertion tool, and wherein the cavity is an annularcavity of a gas turbine engine.
 9. The tool of claim 1, wherein theshell of the first segment is overmolded onto the core, and wherein theshell of the first segment substantially covers an entirety of anexterior of the core.
 10. A tool for inserting into a cavity, the toolcomprising: a plurality of segments moveably coupled to one another,each segment moveable relative to an adjacent segment between a bentposition and a coupled position, the plurality of segments comprising afirst segment, the first segment comprising: a core formed of a firstmaterial; a shell formed of a second material and comprising or defininga guide feature, a drive feature, a line guide, or a combinationthereof; wherein the first material defines a greater stiffness than thesecond material; and wherein the shell comprises the guide feature, andwherein the guide feature is a segment bearing feature.
 11. The tool ofclaim 10, wherein the first material defines a first coefficient offriction, wherein the second material defines a second coefficient offriction, and wherein the first coefficient of friction is at leastabout fifteen percent greater than the second coefficient of friction.12. The tool of claim 10, wherein the segment bearing feature is asegment sliding bearing feature, and wherein the tool further comprises:an insertion tube comprising a tube sliding plain bearing featureconfigured to interact with the segment sliding bearing feature, whereinthe tube sliding plain bearing feature is formed of a third materialdefining a third material hardness greater than a second materialhardness of the second material.
 13. A gas turbine engine comprising: acomponent defining an opening to a cavity within the gas turbine engine;and an insertion tool extending through the opening defined by thecomponent into the cavity, the insertion tool comprising: a plurality ofsegments moveably coupled to one another, each segment moveable relativeto an adjacent segment between a bent position and a coupled position,the plurality of segments comprising a first segment, the first segmentcomprising a core formed of a first material, and a shell formed of asecond material and comprising or defining a guide feature, a drivefeature, a line guide, or a combination thereof, wherein the firstmaterial defines a greater stiffness than the second material, whereinthe core of the first segment is configured to abut a core of a forwardadjacent segment and a core of an aft-adjacent segment.
 14. The gasturbine engine of claim 13, wherein the cavity is an annular cavity ofthe gas turbine engine.
 15. The gas turbine engine of claim 13, whereinthe shell comprises the drive feature, wherein the drive feature is aplurality of gear teeth.
 16. The gas turbine engine of claim 13, whereinthe shell comprises the guide feature, and wherein the guide feature isa segment sliding plain bearing feature.
 17. The gas turbine engine ofclaim 16, wherein the first material defines a first coefficient offriction, wherein the second material defines a second coefficient offriction, and wherein the first coefficient of friction is at leastabout fifteen percent greater than the second coefficient of friction.18. The gas turbine engine of claim 13, wherein the shell comprises theline guide.
 19. The gas turbine engine of claim 13, wherein the drivefeature includes a repeating surface profile on the shell.
 20. The gasturbine engine of claim 13 wherein a tension line extends through theline guide to hold the first segment in the coupled position with anadjacent segment of the plurality of segments.